Re: [exim] Extremely Simple(?) greylisting with exim?

On Fri, 5 Jan 2007, Philip Hazel wrote:

> When a recipient gets a 4xx response, Exim sets up a *recipient* retry
> rather than a host retry, and this is a *routing defer*. So the
> recipient isn't even routed until the retry time arrives (in queue runs).
>
> <goes away and reads code>
>
> However, when the retry time does arrive, it will do the routing and
> then try the hosts according to the host retry times, so I'm not sure if
> this is really a problem at all.
>
> The only way to be sure of Exim's behaviour is to set up a test scenario
> and run it with debugging to see exactly what is going on. After we have
> 4.66 released, I may think about doing this so that I can demonstrate
> how it works.

I have set up a test in which the most preferred host always gives a 4xx
reply to RCPT and the secondary host gives a 4xx reply to connect (thus
generating a "host error"). I have fiddled with retry times for the two
hosts. I cannot get Exim to do anything that seems to be outside its
specification. In my test it behaves as I have described it above.

This is not to say that there might not be some circumstances in which
things go wrong. It's just that I haven't been able to reproduce them.

Philip

--
Philip Hazel, University of Cambridge Computing Service.